Parker



UNITED STATES PATENT OFFICE.

GEORGE WASHINGTON PARKER, OF SAN FRANCISCO, CALIFORNIA.

PROCESS OF TREATING GYPSUM ROCK TO lMlTATE CHALCEDONY.

SPECIFICATION forming part of Letters Patent No. 549,151, dated November5, 1895.

Application filed December 22, 1894- Serial No. 532,652, (No specimens.)

To all whom it may concern:

Be it known that I, GEORGE WASHINGTON PARKER, a citizen of the UnitedStates, re= siding at San Francisco, in the county of San Francisco,State of California, have invented a new and useful Process of TreatingGypsum Rock to Imitate Chalcedony, of which the following is aspecification.

My invention relates in part to processes for treating gypsum rock toimpart to it a hardness and polish resembling marble; but my object isto produce a product not only superior to marble in hardness andfineness of surface, grain, and luster, but resembling in colors andgeneral appearance the different varieties of chalcedony, such as onyx,agate, &c. To this end the crude gypsum rock is first shaped in anydesired form and configuration by carving, sawing, planing, &c., and isthen freed from the water constituting one of its constituent elements,next colored in accordance with the desired effect, and then it istreated to the action of hardening chemical solutions, all as moreparticularly set forth below. Beautiful onyx, agate, 850., effects canbe produced, in accordance with the tastes and desires, in statuary,furniture ornamentations, and the like, and in the finishing of rooms,using the material in lieu of marble or woodwork. By my treatment thecolors are made to appear as if a constituent part or element of therock in its native con.

dition and formation, and the condition of the product, as stated, issuperior in hardness and finish to either marble or chalcedony.

To carry my process into effect, the gypsum rock from the mines havingbeen given the desired configuration, as stated, is submitted to thedrying action of hot air for twelve hours (more or less) until all themoisture has been eliminated. The material is now calcium sulphate,porous from surface to center, and capable of absorbing sufficientchemical solution to produce the desired effect of the rock and colors.To the -surface of the dehydrated rock is now applied the mineral colorssuch as, for an illustration, solution of copper nitrate and aquaammonium, or a solution of sulphate of iron, nitric acid, and potassiumsulpho-cyanide, or other mineral colors. After coloring, the rockisimmersed in asolution of aluminium sulphate (Al (SO for about fifteenhours or until the pores of the rock are completely filled. The materialis then removed and exposed to the open air for a few hours at a lowtemperature and then polished.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent of the United States, is-

The process of treating gypsum rock to represent chalcedony, whichprocess consists in first completely dehydrating the rock by the actionof hot air, next allowing the now porous rock to absorb a solution ofsulphate of iron, nitric acid and potassium sulpho cyanide, after which,immersing in a solution of aluminium sulphate (Al (SO,) for fifteenhours, next exposing to open air and then polishing, substantially asset forth.

In testimony of the foregoing I have hereunto subscribed my name in thepresence of two witnesses.

GEORGE WASHINGTON PARKER.

Witnesses WM. J STUART, HOWARD A. THORNTON.

